No! Burton has made the high back on the 13 Cartels significantly less responsive. Your call whether that is an improvement - sure as hell would not be for me, but it depends on your riding style...
Where are you getting your info from? The 2013 cartel highback has only 3% more torsional flex than the 2012. 3% is not significant.
Are basing your post on handflexing in store or have you ridden the bindings?